Jason to the Rescue

Friday, September 30, 2005

Jo Dodds and John Delaney

Daily Report

The weather this morning was an improvement over the last couple days and spirits were high on board as preparations for a Jason dive were in high gear. But then news traveled quickly about ABE, our autonomous underwater vehicle. ABE was put in the water last night for more mapping runs, but got stuck on the bottom during the night. Fortunately, Jason was getting ready for another dive today and the weather was cooperating. Jason went into the water about 1:30 (GMT 21:30) this afternoon and was able to locate ABE hung up near the sea floor. A floating line wrapped around the length of ABE and was tangled in the bottom propeller. Whatever was attached to the line was gone but its anchor remained and held ABE in place. After lengthy discussion of where to best cut the line, Jason freed ABE. ABE is now on deck and the data has been downloaded. All’s well that ends well.

Along with the rescue of ABE, Jason’s dive plan includes going back to the Main Endeavor vent field to insert an incubator, take water samples to analyze the gasses in the vent, place a seismometer, and test new materials for oxygen sensors. The scientists are all busy getting their instruments in place so that they can collect data to help answer their questions.

The chief engineer, Chuck Petzel, gave a tour of the engine room tonight. Everything is computerized, including the maintenance schedule. When Jason is in the water, there are always two engines operating, otherwise the ship generally runs on one. There is also an emergency engine just in case of power loss. The 1500 kw of power that is produced by the generator could provide 50 homes with power. In addition to power, it is the job of the engineering department to provide fresh water while at sea. This ship uses reverse osmosis to produce up to 7200 gallons of water per day. The seawater passes through several semi-permeable membranes to produce fresh water for the 60 people on board. The engineering team makes sure the everyday things that we take for granted are taken care of.

Jason is currently at work underwater. The dive plan is long since the end of the cruise is nearing and this may be the last dive. There is still much work to be done.

Impressions

John Delaney
University of Washington School of Oceanography

Daily Question

  • What depths can Jason work at? What is the maximum PSI that it can function at, and is it ‘harder’ to operate at greater depths? What is Jason’s maximum mission time?
    Mitch Hetterle ,     Anacortes HS, Anacortes, WA


    Great questions, Mitch. Jason is an incredible ROV (Remotely Operated Vehicle) that can dive to depths of 6501 meters. Jason’s dives along the Endeavour Segment of the Juan de Fuca Plate have been between 2200 and 2400 meters. A cable is unwound from the stern of the ship as Jason and then Medea are launched. It is very important that the tether that connects Medea and Jason does not get wound up or kinked as they descend. The pilot and engineer monitor this carefully all the way down. As they are going down, Jason is under Medea and Medea is directly under the ship. Jason can stay down 70-80 hours before having to come back on deck to have its vitals (oil and such) checked. In winds greater than 25 knots, Jason is not in the water because the ship it’s attached to is moving up and down too much in the waves. It isn’t any harder to work very deep than it is at the surface. The water doesn’t get thicker because of the pressure.

    For every increase of 10 meters (or 33 ft), there is an increase of 1 atmosphere. At sea level this is also 14 pounds per square inch (psi). So at our dive depth on the Endeavour Segment there is approximately 3000 psi of pressure. To answer your question about the maximum psi, at 6500-meter depth, there would be approximately 9100 psi.

  • I learned that pretty much all the animals that live on the hydrothermal vents rely on bacteria but does the bacteria need light to grow there or does it rely on something else?
    Lizzie Lee,     Tolt Middle School, Carnation, WA


    Hi Lizzie. At the hydrothermal vents there are microorganisms that use chemosynthesis reactions to live and grow instead of photosynthesis or energy from the Sun. These bacteria can convert dissolved hydrogen sulfide and methane to provide them with energy. Other bacteria decompose organic matter and they derive their energy in this manner. The chemosynthetic organisms form the base of the food chain. For example, tubeworms depend on chemosynthetic bacteria and in turn, crabs feed on the tubeworms and octopus eat the crabs.